Concentration of oxidized ores of lead, silver, and copper



nlime lllllt lltltlltl i the EDWARD H. SNYDER AND WILLIAM: ll). GREEN, Olli BAUER. U'llll-lt, ltSSIGl-ll'flltt-Sl T0 COM- BINED METALS REDUCTION GOMPAN'EE,

1 UTAH 0F STOCKTON, UTAH, ill CORPORATION 0.?

tZUhTUENTEAT'ION 01E OKIlDlIZED 011E115 Oil? LEI-ll), SILVER, .llllll] UUPlil illEt lilo Drawing.

This invention relates to the concentration of oxidized ores of lead, silver and copper by flotation. The concentration of sullid ores by flotation is extensively practiced; but the attempt to concentrate oxidized ores by flotation involves considerable difficulties, especially When the ore contains considerable quantities of iron oxide, manganese oxide, shale, clay or other materials that tend to form large quantities of slow settling slinies. Although there are enormous quantities of oxidized ores of this type and numerous attempts have been made to devise a practical process for concentrating them by flotation, it has heretofore been commercially impracticable to concentrate such ores by flotation, due principally to the 10W recoveries on account of the gangue aggregates including much valuable mineral and due also to the concentrates being of low grade on account of the entrainment of slow settlingslinics by the froth.

The principal object of the present invention is to overcome such difficulties and devise a practical process of concentrating oxidized ores of lead, silver and copper by flotation and especially such oxidized ores as contain material that tend to form slovv settling slirnes.

In the ordinary process of flotation, the ore is finely ground in a ball mill or the like, "Water is added thereto to form a pulp, and the pulp is passed into a flotation cell alongwith a small quantity of oil or other frothing agent and agitated with air or otherwise treated so as to form a froth which collects at the surface of the cell, which froth contains most of the valuable mineral and is removed at the surface of the cell While most of the gangue material is removed at a lower point. .dLS stated above, processes of this type are extensively used in the treatment of sullid ores According to the present invention, oxidized or partly oxidized ores of lead, silver and/or copper :1 re used, and the treatment of the pulp in the flotation cell is effected in the presence of sodium chloride and sodium sulfid, the treatment in other respects followcominon notation practice. The sodium Application filed January 25, 1928.- Serial No. WlFJJlEld.

chloride may be lllllflfllltoll in the dry form into the ore in the ball mill: but is preferably added in the form of a solution either to the pulp or to the ore itscl l- Likewise the sodium sullid may be added either in the dry form or in a solution at fllly lmlllt, provided it has sullicicnt time to react throughout the pulp before the cell treatment of the pulp is completed. In most cases it is preferable to mix the sodium sullid in dry form with the ore in the ball mill. The quantities of sodium chloride and sodium sullid are subject to rariation dependent on the characteristics of the ore.

The use of sodium chloride and sodium Sill fid in the flotation treatment of oxidized ores of lead, silver and copper results in a very shtisfactory recovery of the valuable mineral and in a high concentration thereof in the froth. .rlp 'iarently the action of the sodium chloride is to disperse the ganp'ue material and thereby prevent it from adhering to the silver, lead and copper minerals and to prevent it from being carried into the froth. ilfter trcatn'ient with sodium chloride the particles of valuable mineral appear to be left fairly clean and unreliable to reaction with the sullid. Such reaction results in converting some of the aluable oxidized mineral into a sulfid or in formin a suliid coating thereon that causes such modified mineral to art after the manner of a natural suliid.

llt may be that there is a reaction of the sodium chloride with the valuable mineral as an intermediate step in the conversion of part of the valuable mineral into sullld. l'lovvci'er this may be, the use of sodium chloride in connection with the sullid very ,u'reatly enhances the recovery of the valuable mineral and increases the decree of concentration thereof and the grade of the concentrate "Whereas the attempt to sullidizc the mineral in a "Water pulp would result in poor recovery and a low grade comcntrate.

The practice of the invention will be illus trated by the following examples:

amnple fi o. 1

ill chance of oatidizcd ore of silver and lead -uas ground in ball mill with a quantity of sodium chloride equivalentto 400 pounds per ton of ore and a quantity of sodium sulfid I equivalent to 6 pounds per ton of ore together with sufficient water to make a 1 to 1 pulp. When the grinding was completed the charge was removed from the ball mill, diluted with' water to 30% solids and treated in a flotation cel in accordance with ordinary flotation practice. A high grade concentrate contain- Tail ing most of the oxidized silver and lead was obtained, as will appear from the following tabulation, namely:

Assays of products Product Ozs. Ag f ggy Heads 17. 98 27. 6 41-. 0 Concentrate 29. 42 43.8 17. 0 Cleaner tallings 8.81 17. 5 63. 2 Final tailings 4. 83 3. 5 66.8

The following tabulation shows the percentages of the total silver and lead contained in the ore that wererecoveredin various products as well as the percentage of the total weight represented by each product:

Percent. of Percent-of Percent. of

Product total weight total silver total lead Heads 100. 0 100. 0 100. 0 Concentrate 55. 8 87. 2 91. 8 Cleaner tailings.-. 3. 8 1.8 2.6 Final tailings 40. 4 11. 0 5. 6

Example N 0. 2

A charge of oxidized ore of silver and lead was ground in a ball mill with a quantity of sodiumchloride equivalent to 200 pounds per ton of ore and a quantity of sodium sulfid equivalent to 12 pounds per ton of ore together with sufficient'water to make a 1 to l pulp. \Vhen the grinding was completed the charge was removed from the ball mill, diluted with water to 30% solids and treated in a flotation cell with .01 pound of pine oil per ton of ore. A high grade concentrate containing most of the oxidized silver and lead was obtained, as will appear from the following tabulation, namely:

Assay of products Per- Per- Per- Ounces Ounces Product cent cent. cent. 511V 80 lead insol. iron Heads 12. 69 0. 11 20. 4 55. 1 6. 6 Concentrate 36. 23 0. 185 54. 6 16. 4 1. 7 Cleaner tailings. 9. 75 0. 120 14. 1 56.0 9. 2 Final product 5.88 0.080 9.7 61. 6 9.8 Finaltailings .3. 08 0.060 2. 1 81. 4 6. 4

The percentages of the total silver, gold, and lead contained in the ore that were recovered in the various products, as well as the percentage of the total weight of the heads represented by each product, are shown in the following tabulation:

Percent. Percent. Percent. Percent Product cttotal of total of total of total .weight silver gold lead Heads 100.0 100. 0 100. 0 100. 0 Concentrate 27. 6 71. 5 46.0 75. 2- Gleanerv tailings 22 0 15. 2 24. 2 v15. 5 Final product- 10.6 4. 5 7. 8 5. 1 ings 39. 8 8. 8 22. 0 4. 2

It is noted that if an ore contains a sulfid or sulfids that are amenable to concentration by ordinary flotation practice, the flotability of such sulfid portion is not adversely affected by our process of conditioning the ore; but on the contrary, the dispersion and deflo'cculation of the gangue due to the sodium chloride expedite the flotation and enhance the recovery of such sulfid portion.

Our process is thus applicable not only to fully oxidized ores but to ores that are only artly oxidized, that is,-ores that contain suld mineral as well as oxidized mineral.

It is obviously a great advantage of our process that it conditions ores for flotation treatment that have heretofore not been economically amenable to flotation treatment, es

'peci'ally oxidized ore associated with gangue containing large quantities of iron oxide,

' manganese oxide,'shale, clay or other matter that tends to form slow settling slimes. The

bromyrite, einbolite; and the oxidized minerals of copper include cuprite, malachite, azurite, tenorite.

It is noted that sodium sulfid is a sulfidizingagent and is used as such in our process,

but instead of sodium sulfid, it is practicable to substitute thesulfid of any alkali or alkaline earth metal. Ordinarily about one to twelve pounds of sodium sulfid per ton of ore is suificient for practical purposes.

In the first example above set forth, 400 pounds of sodium chloride were used per ton of ore representing a brine containing about two hundred and fifty grams per liter of water whereas in the second example only 200 pounds of sodium chloride per ton of ore] were used representing a brine containing about one hundred and'twenty-five grams of lyreaaeet sodium chloride per liter of water. We have found in practice that satisfactory results have been secured when 50 pounds per ton of ore was used with some ores. in practice, the quantity of sodium. chloride used is gg'riator for ores containing high percentages of iron oxide or clayey gangue material than is required for ores with clean quartz gangue; but. as it is a simple matterto recover the sodium chloride by suitable apparatus, the

proportion of sodium chloride admits of considerable variation without much effect on the efficiency or economy of the ope 'ation.

As in most chemical proceses, chemi 'al reactions of the present process are stimulated by heat. Ordinarily, it is desirable to heat the pulp to a temperature of about Eltl to lot) Fahrenheit. as we have found very satisfactory results with such temperature. on With a lower temperature, the reactions are slower. whereas the cost of heating the pulp to a higher temperature makes it undesirable. The du 'ation of the treatment of the ore pulp with sodium chloride and alkali sule53 tid varies somewhat in practice in accordance with ordinary flotation inactice, the time interval ringing from abcut two minutes with some ore to twenty minutes with other ore. lo the ordinary process of flotation, a small quantit of oil. usually a small fraction of one percent by weight of the ore, is used as a frothing aeent; amt in accordance with con1- mon practice, we generally use a small fraction of one percent of oil for such purpose. Our experiments indicate, however, that sodium chloride is itself a frothing agent and we have successfully concentrated certain ores by our process: without adding ll or any other frothinp,- agentexcept sodium chloride. 49 The test given as Example No. 1 above was made without the use of oil.

What we claim is. 1. The improvement in the flotation concentration of ores containing oxidized min- 5 erals of lead. silver or copper which consists in comlitioning the ore with sodium chloride and a sultidizin; agent: preparatory to froth flotation thereof.

The improvement in the flotation com 5!) centration of ores containim oxidiznl minerals of lead, silvcr or copper which consists in conditioning the ore in the form of a nonacid pulp with sodium chloride and a sultidizing aeent preparatory to froth flotation 53 thereof.

3. The improvement in'the flotation concentration of ores containingoxidized minerals of lead, silver or copper which consists in forming the ore into a non-acid pulp contain- 69 iug sodium chloride in the propm'tion of from about five to about twenty per cent of the weight of the dry ore.

t The improvement in the flotation concentration of ores containing oxidized mitt C5 crals of lead, silver or copper which c nsists in forming the oreinto a pulp containing sodium chloride in solution in the propor tion of from about five to about twenty percent of the weight of the dry ore and about one percent of a sultidizine' agent. per ton of dry ore preparatory to froth flotation thereof.

5. The improvement in the flotation concentration of ores containing: oxidized minerals of lead, silver or copper which consists in forming the ore into a pulp containing sodium chloride in solution in the proportion of from about one hundred gains to about two hundred and fifty grams of sodium chloride per liter of solution and about one pen cent of a sultidizinn' agent per ton of dry ore amlsubjtwtinp; such pulp to froth flotation.

(3. The im 'n'mement' in the froth flotation concentration of ores containing oxidized minerals of lead. silver or copper which consists in forming the ore into a pulp containing sodium chloride in the l'n'oportion of from about ten to about twenty percent of the weight of the dry ore and about one percent of an alkali sullid and subjecting such pulp to froth flotation.

7. The imtn'o'vement in the froth flotation concentration of ores containing oxidized minerals of lead, silver or copper which consists in forming the ore into a pulp containin; sodium chloride in the proportion of from about ten to about twenty percent of the weight of the dry ore and about dne per cent of sodium sullid and subjecting such pulp to froth flotation.

h. The process of concent 'ating ores containing oxidized mine als of lead, silver or copper which consists in adding thereto sodium chloride and a sultidizine' agent and forming the same into a pulp. subjecting such pulp to froth flotation and recovering the resultant froth.

9. The process of concentratiup ores containine oxidized minerals of lead. silver or copper which consists in forming the same into a pulp containing sodium chloride and a sulfidizing agent, subjecting such pulp to froth flotation and recovering the re ulting froth, the weight of the sodium chloride being from about 200 pounds to about oo pounds per ton of dry ore.

if). The process of com-entratine' ores co|1- taming oxidized minerals of lead. silver or copper which consists in forming the same into a pulp containing sodium chloride and sodium sullid, suljijecting such pulp to froth flotation and recovering the resulting froth. the weight of the sodium chloride beinp' from about LZtJt) pounds to about too pounds per ton of dry ore and the weight of sodium sullid bcine' abou seven to twelve pounds per ton of dry ore.

ll "The process of cmmcntratinrr ores containing oxidized minerals oflead, silver or copper which consists in forming the :dlltlt .into a pulp containing: sodium chloride :11. l

llTi

lZii

llltli sodium sulfid, subjecting such pulp to froth flotation and recovering the resulting froth, the Weight of the sodium chloride in the pulp being from about 100 grains per liter of water to about 250 grams per liter of water and the weight of sodium sulfid being about seven to twelve pounds per ton of dry ore.

Signed at Bauer, Utah, this 13th day of January, 1928.

- EDWARD H. SNYDER.

WILLIAM D. GREEN. 

